I think this is from the Yoast SEO plugin, but not positive. It updated this morning, and I only noticed it today.

Every new post and draft (and if I update an already published post) has a custom field variable name yst_is_cornerstone showing with an empty value. It won't delete. Deleting doesn't do anything. Changing the value and name and hitting update results in it being re-added in addition to whatever I tried changing it to.

I'm worried it is some type of infection because the only Google result for yst_is_cornerstone brings up a sketchy page.

Anyone know what this is / how to remove it?

Update: I just did a database query, and the yst_is_cornerstone only appears in the meta of new posts, it hasn't been added to every single post. But each time I update a post or create a new one, it is added.

Update 2: The field doesn't save values. Anything inputted disappears as soon as it is saved.

4 Answers 4


Yes, this is a new Yoast SEO feature. It's a checkbox, so as long a you don't select it in the SEO-metabox, the value will be zero/empty. I presume it's overwritten every time the post is saved, hence it won't delete or accept a value written directly into the database table.

There doesn't seem to be a setting in the dashboard, so in order to disable it you'll have to search the code for a filter or contact Yoast.


To disable that custom field, go to Yoast SEO > Dashboard > Features.

Pic of screenshot

Read more about cornerstore content


The best way to figure out what is going on is to disable your plugins and see if it goes away.

Rename your plugins folder to something else. Does this fix the issue?

If it does rename the plugin folder back to plugins. Now you have to enable 1 by 1 each plugin and check if all still is working. When all seems okay then at least you found a solution but still have no answer about the 'why was it not working' but it would be too far to dig into that issue but at least now you can take some time to find out what is causing that field to appear.

Are you using x theme? It could be that theme itself so try switching themes as well.

  • The site is currently getting a decent amount of traffic and disabling some of the plug-ins will break the URLs and cause some pretty big issues. I have disabled some of the plug-ins already and then nothing .. I'm using a very minimal custom theme, so that is it the issue
    – jonbon
    Commented Apr 11, 2017 at 15:37

Yes it seems to be SEO Yoast, any posts done with the updated plugin active will add the text, deactivating the plugin and creating a new post does not produce the unwanted yst_is_cornerstone, however, it still remains on the posts done with the plugin active, how strange and annoying!

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